/*
 * Copyright (C) 2010 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package libcore.io;

import com.jtransc.io.SizeOf;

import java.nio.ByteOrder;

/**
 * Iterates over big- or little-endian bytes in a Java byte[].
 *
 * @hide don't make this public without adding bounds checking.
 */
public final class HeapBufferIterator extends BufferIterator {
	private final byte[] buffer;
	private final int offset;
	private final int byteCount;
	private final ByteOrder order;

	private int position;

	HeapBufferIterator(byte[] buffer, int offset, int byteCount, ByteOrder order) {
		this.buffer = buffer;
		this.offset = offset;
		this.byteCount = byteCount;
		this.order = order;
	}

	public void seek(int offset) {
		position = offset;
	}

	public void skip(int byteCount) {
		position += byteCount;
	}

	public void readByteArray(byte[] dst, int dstOffset, int byteCount) {
		System.arraycopy(buffer, offset + position, dst, dstOffset, byteCount);
		position += byteCount;
	}

	public byte readByte() {
		byte result = buffer[offset + position];
		++position;
		return result;
	}

	public int readInt() {
		int result = Memory.peekInt(buffer, offset + position, order == ByteOrder.LITTLE_ENDIAN);
		position += SizeOf.INT;
		return result;
	}

	public void readIntArray(int[] dst, int dstOffset, int intCount) {
		final int byteCount = intCount * SizeOf.INT;
		Memory.unsafeBulkGet(dst, dstOffset, byteCount, buffer, offset + position, SizeOf.INT, order != ByteOrder.nativeOrder());
		position += byteCount;
	}

	public short readShort() {
		short result = Memory.peekShort(buffer, offset + position, order == ByteOrder.LITTLE_ENDIAN);
		position += SizeOf.SHORT;
		return result;
	}

	/**
	 * Returns a new iterator over {@code buffer}, starting at {@code offset} and continuing for
	 * {@code byteCount} bytes. Items larger than a byte are interpreted using the given byte order.
	 */
	public static BufferIterator iterator(byte[] buffer, int offset, int byteCount, ByteOrder order) {
		return new HeapBufferIterator(buffer, offset, byteCount, order);
	}
}
